Check The Stop Lamp Switch Circuit

Check that stop lamp lights up when brake pedal is depressed and turns off when brake pedal is released.
Measure the voltage between terminal 23 of the ESP control module harness side connector and body ground when brake pedal is depressed.
Specification: approximately B+

Fig 1: Measure Voltage Between Terminal 23 Of ESP Control Module Harness Side Connector & Body Ground
Courtesy of KIA MOTORS AMERICA, INC.
Is the voltage within specification?
YES
- Check the hydraulic circuit for leakage.
NO
- Repair the stop lamp switch. Repair an open in the wire between the ESP control module and the stop lamp switch.